Bioprosthetic heart valves include valve leaflets formed of flexible biological material. Bioprosthetic valves from human donors are referred to as homografts, whereas such valves from non-human animal donors are referred to as xenografts. These valves as a group are known as tissue valves. The tissue may include donor valve leaflets or other biological materials such as bovine or porcine pericardium, which are formed into the new valve structure. Depending on the method of implantation, the prosthetic valve structure may be sewn directly into place within a patient or attached to a second structure, such as a stent or other prosthesis, for implantation into a patient.
Conventional implantation of prosthetic tissue valves into the patient's body has been accomplished by invasive surgical procedures. Access to the heart valves (tricuspid, pulmonary, mitral, aortic), for instance, generally includes a thoracotomy or a sternotomy for the patient, and may include placing the patient on heart bypass to continue blood flow to vital organs, such as the brain, during the surgery. Thus, recovery from “open-heart” surgery often requires a great deal of time.
Recently percutaneous methods using catheter-based delivery mechanisms that traverse the vasculature to a treatment site have been developed allowing for minimally-invasive heart valve replacement and very short patient recovery times. Implantation of a prosthetic tissue valve percutaneously or by implantation using thoracic-microsurgery techniques is a far less invasive act than the surgical operation required for implanting traditional cardiac valve prostheses. Prosthetic tissue valves deliverable by these less invasive methods typically include an anchoring structure for supporting and fixing the valve prosthesis in the implantation position, to which the prosthetic valve leaflets are stably connected.
As mentioned above, some tissue valves are fashioned from xenografts taken from, for instance, a pig, horse, or cow, and others are fashioned from homografts taken from another human. The natural tissue for the replacement valves may be obtained from, for example, heart valves, aortic roots, aortic walls, aortic leaflets, pericardial tissue such as pericardial patches, bypass grafts, blood vessels, human umbilical tissue and the like. These natural tissues are typically soft tissues, and generally include collagen containing material. The tissue can be living tissue, decellularized tissue or recellularized tissue. The natural tissue can be fixed by crosslinking to provide mechanical stabilization, for example, by preventing enzymatic degradation of the tissue prior to implantation. A solution of glutaraldehyde or formaldehyde is typically used for fixation.
Preferably, the prosthetic tissue valves will be suspended in the glutaraldehyde storage solution until the surgical or percutaneous procedure is about to begin. As such when used in a catheter-based procedure, the clinician must prepare the fixed prosthetic tissue valve for insertion within the vasculature by removing the prosthetic tissue valve from the glutaraldehyde storage solution and rinsing the prosthetic tissue valve to remove the glutaraldehyde storage solution, followed by loading the prosthetic tissue valve onto or within the catheter-based delivery system. The clinician must take care during the preparation and loading steps not to contaminate or damage the prosthetic tissue valve. Such preparation adds time to the interventional procedure as well as risk that the tissue valve may not be properly loaded onto the catheter-based delivery system, which can lead to serious complications upon implantation of the prosthetic tissue valve at the treatment site. Due to the complexity and criticality of loading the prosthetic tissue valve onto the catheter-based delivery device, some vendors of replacement tissue valves actually provide representatives at the time of implantation to perform this aspect of the interventional procedure.
One solution to address proper loading concerns would be to “pre-load” the prosthetic tissue valve onto the catheter-based delivery system prior to shipment; however, prosthetic tissue valves heretofore have not been pre-loaded due to the sensitivity of the prosthetic tissue valves to prolonged crimping, as well as the necessity of maintaining the prosthetic tissue valve within a storage solution until just prior to implantation. Thus, there remains a need in the art for bioprosthetic valve packaging that can assure the sterility and integrity of a prosthetic tissue valve during shipment and ease loading of the prosthetic tissue valve onto a catheter-based delivery system by a clinician prior to performing the interventional procedure.